S9+ They say there is an update to Q but

[SuzieQ]

@Randy

Vendor image on the device is NOT compatible
Expected Android 10 vendor

This thread about Samsung Galaxy S9+ (star2lte) and S9 (starlte) was closed four good hours ago:

@SuzieQ

If the LineageOS Wiki is to be believed, it is a basic requirement to also update the Android firmware before flashing the new OS - and this is a Samsung-Android-10-Firmware.